The Golden Gate Bridge in San Francisco, California, is a catenary suspension bridge, which is very similar in appearance to a parabola. The main span cables are suspended between two towers that are 4200 feet apart and 500 feet above the roadway. The cable extends 10 feet above the roadway midway between the two towers.
a. Find an equation that models the shape of the cable.
b. How far from the roadway is the cable 720 feet from the bridge's center?
